stm32f4-nucleo-test/libopencm3/tests/gadget-zero/delay.c

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/*
* This file is part of the libopencm3 project.
*
* Copyright (C) 2017 Karl Palsson <karlp@tweak.net.au>
*
* This library is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* This file implements some simple busy timers. They are designed to be
* portable, not performant.
* TIM6 is appropriated for usage.
*/
#include <stdint.h>
#include <libopencm3/stm32/rcc.h>
#include <libopencm3/stm32/timer.h>
#include "delay.h"
void delay_setup(void)
{
/* set up a microsecond free running timer for ... things... */
rcc_periph_clock_enable(RCC_TIM6);
/* microsecond counter */
timer_set_prescaler(TIM6, rcc_apb1_frequency / 1000000 - 1);
timer_set_period(TIM6, 0xffff);
timer_one_shot_mode(TIM6);
}
void delay_us(uint16_t us)
{
TIM_ARR(TIM6) = us;
TIM_EGR(TIM6) = TIM_EGR_UG;
TIM_CR1(TIM6) |= TIM_CR1_CEN;
//timer_enable_counter(TIM6);
while (TIM_CR1(TIM6) & TIM_CR1_CEN);
}